Movement detection sensors have so far been proposed as movement detection devices for detecting the movement of an object such as a person, in a space such as a bathroom. As a typical example, there has been a monitoring apparatus for monitoring the breath of a sleeping person on a bed by projecting a pattern onto the sleeping person on the bed, continuously taking an image of the projected pattern, and calculating the shift amount of the pattern from the image taken continuously (See Patent Document 1, for example).    Patent Document 1: JP-A-2002-175582 (pp 5-9 and FIGS. 1-13)